This invention relates to a technique for forming the shoulder and neck of a squeeze tube such as the type used for toothpaste. More particularly, this invention involves a technique for forming the inner wall of the shoulder and neck from an upward extension of the collapsible sidewall.
The collapsible sidewall of the squeeze tube is cylindrical. The head portion has an inwardly extending shoulder and an upwardly extending substantially cylindrical neck. The neck is threaded to receive a cap.
The shoulder and neck portions are normally molded as a rigid piece of, for example, polyethylene, onto the top of the sidewall. The plastic head frequently requires an impervious insert to prevent oxygen from passing into the container and to prevent flavorants and other constituents of the produce from passing out through the molded head. The sidewall is usually a multi-ply material having at least one metal ply to provide this impervious layer. One multi-ply sidewall arrangement is described in U.S. Pat. No. 3,295,725 issued to R. Brandt on Jan. 3, 1967 and impervious insert arrangements for the head are described in U.S. Pat. Nos. 3,260,411 issued to F. E. Dobson on July 12, 1966 and 3,565,293 issued to R. Schulty on Feb. 23, 1971.
If the sidewall could be extended upward into the head portion of the squeeze tube, that would provide the required impervious layer. However, because the shoulder slopes in and the neck has a diameter less than that of the sidewall, it becomes very difficult to bend and fold and shape the sidewall into a useable shape on which the rigid head could then be molded. Suggestions for so extending the sidewall are shown in U.S. Pat. No. 2,176,109 issued to J. P. Ratay on Apr. 4, 1939. But, such suggestions have not been followed because of the difficulty of forming the shoulder and neck from an extension of the sidewall. Accordingly, it is a major purpose of this invention to provide an apparatus and method for forming a shoulder and neck layer from an upward extension of the sidewall.
It is an important purpose of this invention to provide this impervious layer in a fashion that is both reliable and repeatable so that the head will be reliably impervious and so that the shape formed will be repeated each time the operation is performed on a separate tube.
It is further important that each objective be achieved with a mechanism and through a method that is fast acting and that is economical.